/*
 * ZeroTier One - Global Peer to Peer Ethernet
 * Copyright (C) 2012-2013  ZeroTier Networks LLC
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * --
 *
 * ZeroTier may be used and distributed under the terms of the GPLv3, which
 * are available at: http://www.gnu.org/licenses/gpl-3.0.html
 *
 * If you would like to embed ZeroTier into a commercial application or
 * redistribute it in a modified binary form, please contact ZeroTier Networks
 * LLC. Start here: http://www.zerotier.com/
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>

#include <openssl/sha.h>

#include "RuntimeEnvironment.hpp"
#include "NodeConfig.hpp"
#include "Network.hpp"
#include "Switch.hpp"
#include "Packet.hpp"
#include "Utils.hpp"

namespace ZeroTier {

void Network::Certificate::_shaForSignature(unsigned char *dig) const
{
	SHA256_CTX sha;
	SHA256_Init(&sha);
	unsigned char zero = 0;
	for(const_iterator i(begin());i!=end();++i) {
		SHA256_Update(&sha,&zero,1);
		SHA256_Update(&sha,(const unsigned char *)i->first.data(),i->first.length());
		SHA256_Update(&sha,&zero,1);
		SHA256_Update(&sha,(const unsigned char *)i->second.data(),i->second.length());
		SHA256_Update(&sha,&zero,1);
	}
	SHA256_Final(dig,&sha);
}

static const std::string _DELTA_PREFIX("~");
bool Network::Certificate::qualifyMembership(const Network::Certificate &mc) const
{
	// Note: optimization probably needed here, probably via some kind of
	// memoization / dynamic programming. But make it work first, then make
	// it fast.

	for(const_iterator myField(begin());myField!=end();++myField) {
		if (!((myField->first.length() > 1)&&(myField->first[0] == '~'))) { // ~fields are max delta range specs
			// If they lack the same field, comparison fails.
			const_iterator theirField(mc.find(myField->first));
			if (theirField == mc.end())
				return false;

			const_iterator deltaField(find(_DELTA_PREFIX + myField->first));
			if (deltaField == end()) {
				// If there is no delta, compare on simple equality
				if (myField->second != theirField->second)
					return false;
			} else {
				// Otherwise compare range with max delta. Presence of a dot in delta
				// indicates a floating point comparison. Otherwise an integer
				// comparison occurs.
				if (deltaField->second.find('.') != std::string::npos) {
					double my = strtod(myField->second.c_str(),(char **)0);
					double their = strtod(theirField->second.c_str(),(char **)0);
					double delta = strtod(deltaField->second.c_str(),(char **)0);
					if (fabs(my - their) > delta)
						return false;
				} else {
#ifdef __WINDOWS__
					int64_t my = _strtoi64(myField->second.c_str(),(char **)0,10);
					int64_t their = _strtoi64(theirField->second.c_str(),(char **)0,10);
					int64_t delta = _strtoi64(deltaField->second.c_str(),(char **)0,10);
#else
					int64_t my = strtoll(myField->second.c_str(),(char **)0,10);
					int64_t their = strtoll(theirField->second.c_str(),(char **)0,10);
					int64_t delta = strtoll(deltaField->second.c_str(),(char **)0,10);
#endif
					if (my > their) {
						if ((my - their) > delta)
							return false;
					} else {
						if ((their - my) > delta)
							return false;
					}
				}
			}
		}
	}

	return true;
}

const char *Network::statusString(const Status s)
	throw()
{
	switch(s) {
		case NETWORK_WAITING_FOR_FIRST_AUTOCONF: return "WAITING_FOR_FIRST_AUTOCONF";
		case NETWORK_OK: return "OK";
		case NETWORK_ACCESS_DENIED: return "ACCESS_DENIED";
	}
	return "(invalid)";
}

Network::~Network()
{
	delete _tap;

	if (_destroyOnDelete) {
		std::string confPath(_r->homePath + ZT_PATH_SEPARATOR_S + "networks.d" + ZT_PATH_SEPARATOR_S + toString() + ".conf");
		std::string mcdbPath(_r->homePath + ZT_PATH_SEPARATOR_S + "networks.d" + ZT_PATH_SEPARATOR_S + toString() + ".mcerts");
		Utils::rm(confPath);
		Utils::rm(mcdbPath);
	} else {
		// Causes flush of membership certs to disk
		clean();
	}
}

SharedPtr<Network> Network::newInstance(const RuntimeEnvironment *renv,uint64_t id)
	throw(std::runtime_error)
{
	char tag[32];
	sprintf(tag,"%.16llx",(unsigned long long)id);

	// We construct Network via a static method to ensure that it is immediately
	// wrapped in a SharedPtr<>. Otherwise if there is traffic on the Ethernet
	// tap device, a SharedPtr<> wrap can occur in the Ethernet frame handler
	// that then causes the Network instance to be deleted before it is finished
	// being constructed. C++ edge cases, how I love thee.
	SharedPtr<Network> nw(new Network());
	nw->_ready = false; // disable handling of Ethernet frames during construct
	nw->_r = renv;
	nw->_tap = new EthernetTap(renv,tag,renv->identity.address().toMAC(),ZT_IF_MTU,&_CBhandleTapData,nw.ptr());
	memset(nw->_etWhitelist,0,sizeof(nw->_etWhitelist));
	nw->_id = id;
	nw->_lastConfigUpdate = 0;
	nw->_destroyOnDelete = false;
	if (nw->controller() == renv->identity.address()) // sanity check, this isn't supported for now
		throw std::runtime_error("cannot add a network for which I am the netconf master");
	nw->_restoreState();
	nw->_ready = true; // enable handling of Ethernet frames
	nw->requestConfiguration();
	return nw;
}

void Network::setConfiguration(const Network::Config &conf)
{
	Mutex::Lock _l(_lock);
	if ((conf.networkId() == _id)&&(conf.peerAddress() == _r->identity.address())) { // sanity check
		//TRACE("network %.16llx got netconf:\n%s",(unsigned long long)_id,conf.toString().c_str());
		_configuration = conf;
		_myCertificate = conf.certificateOfMembership();
		_lastConfigUpdate = Utils::now();

		_tap->setIps(conf.staticAddresses());
		_tap->setDisplayName((std::string("ZeroTier One [") + conf.name() + "]").c_str());

		memset(_etWhitelist,0,sizeof(_etWhitelist));
		std::set<unsigned int> wl(conf.etherTypes());
		for(std::set<unsigned int>::const_iterator t(wl.begin());t!=wl.end();++t)
			_etWhitelist[*t / 8] |= (unsigned char)(1 << (*t % 8));

		std::string confPath(_r->homePath + ZT_PATH_SEPARATOR_S + "networks.d" + ZT_PATH_SEPARATOR_S + toString() + ".conf");
		if (!Utils::writeFile(confPath.c_str(),conf.toString())) {
			LOG("error: unable to write network configuration file at: %s",confPath.c_str());
		}
	}
}

void Network::requestConfiguration()
{
	if (controller() == _r->identity.address()) {
		LOG("unable to request network configuration for network %.16llx: I am the network master, cannot query self",(unsigned long long)_id);
		return;
	}
	TRACE("requesting netconf for network %.16llx from netconf master %s",(unsigned long long)_id,controller().toString().c_str());
	Packet outp(controller(),_r->identity.address(),Packet::VERB_NETWORK_CONFIG_REQUEST);
	outp.append((uint64_t)_id);
	outp.append((uint16_t)0); // no meta-data
	_r->sw->send(outp,true);
}

void Network::addMembershipCertificate(const Address &peer,const Certificate &cert)
{
	Mutex::Lock _l(_lock);
	if (!_configuration.isOpen())
		_membershipCertificates[peer] = cert;
}

bool Network::isAllowed(const Address &peer) const
{
	// Exceptions can occur if we do not yet have *our* configuration.
	try {
		Mutex::Lock _l(_lock);
		if (_configuration.isOpen())
			return true;
		std::map<Address,Certificate>::const_iterator pc(_membershipCertificates.find(peer));
		if (pc == _membershipCertificates.end())
			return false;
		return _myCertificate.qualifyMembership(pc->second);
	} catch (std::exception &exc) {
		TRACE("isAllowed() check failed for peer %s: unexpected exception: %s",peer.toString().c_str(),exc.what());
	} catch ( ... ) {
		TRACE("isAllowed() check failed for peer %s: unexpected exception: unknown exception",peer.toString().c_str());
	}
	return false;
}

void Network::clean()
{
	std::string mcdbPath(_r->homePath + ZT_PATH_SEPARATOR_S + "networks.d" + ZT_PATH_SEPARATOR_S + toString() + ".mcerts");

	Mutex::Lock _l(_lock);

	if (_configuration.isOpen()) {
		_membershipCertificates.clear();
		Utils::rm(mcdbPath);
	} else {
		FILE *mcdb = fopen(mcdbPath.c_str(),"wb");
		bool writeError = false;
		if (!mcdb) {
			LOG("error: unable to open membership cert database at: %s",mcdbPath.c_str());
		} else {
			if ((writeError)||(fwrite("MCDB0",5,1,mcdb) != 1)) // version
				writeError = true;
		}

		for(std::map<Address,Certificate>::iterator i=(_membershipCertificates.begin());i!=_membershipCertificates.end();) {
			if (_myCertificate.qualifyMembership(i->second)) {
				if ((!writeError)&&(mcdb)) {
					char tmp[ZT_ADDRESS_LENGTH];
					i->first.copyTo(tmp,ZT_ADDRESS_LENGTH);
					if ((writeError)||(fwrite(tmp,ZT_ADDRESS_LENGTH,1,mcdb) != 1))
						writeError = true;
					std::string c(i->second.toString());
					uint32_t cl = Utils::hton((uint32_t)c.length());
					if ((writeError)||(fwrite(&cl,sizeof(cl),1,mcdb) != 1))
						writeError = true;
					if ((writeError)||(fwrite(c.data(),c.length(),1,mcdb) != 1))
						writeError = true;
				}
				++i;
			} else _membershipCertificates.erase(i++);
		}

		if (mcdb)
			fclose(mcdb);
		if (writeError) {
			Utils::rm(mcdbPath);
			LOG("error: unable to write to membership cert database at: %s",mcdbPath.c_str());
		}
	}
}

Network::Status Network::status() const
{
	Mutex::Lock _l(_lock);
	if (_configuration.containsAllFields())
		return NETWORK_OK;
	return NETWORK_WAITING_FOR_FIRST_AUTOCONF;
}

void Network::_CBhandleTapData(void *arg,const MAC &from,const MAC &to,unsigned int etherType,const Buffer<4096> &data)
{
	if (!((Network *)arg)->_ready)
		return;
	const RuntimeEnvironment *_r = ((Network *)arg)->_r;
	if (_r->shutdownInProgress)
		return;
	try {
		_r->sw->onLocalEthernet(SharedPtr<Network>((Network *)arg),from,to,etherType,data);
	} catch (std::exception &exc) {
		TRACE("unexpected exception handling local packet: %s",exc.what());
	} catch ( ... ) {
		TRACE("unexpected exception handling local packet");
	}
}

void Network::_restoreState()
{
	std::string confPath(_r->homePath + ZT_PATH_SEPARATOR_S + "networks.d" + ZT_PATH_SEPARATOR_S + toString() + ".conf");
	std::string confs;
	if (Utils::readFile(confPath.c_str(),confs)) {
		try {
			if (confs.length()) {
				Config conf(confs);
				if (conf.containsAllFields())
					setConfiguration(conf);
			}
		} catch ( ... ) {} // ignore invalid config on disk, we will re-request
	} else {
		// If the conf file isn't present, "touch" it so we'll remember
		// the existence of this network.
		FILE *tmp = fopen(confPath.c_str(),"w");
		if (tmp)
			fclose(tmp);
	}
	// TODO: restore membership certs
}

} // namespace ZeroTier